The relationship between internal chain length of amylopectin and crystallinity in starch.
The relationship between internal chain length of amylopectin and crystallinity in starch.
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DOI：
10.1002/(sici)1097-0282(19991005)50:4
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发表时间：
1999-10
期刊：
影响因子：
2.9
通讯作者：
A. C. O'sullivan;S. Pérez
中科院分区：
文献类型：
--
作者：
A. C. O'sullivan;S. Pérez
建立了支链淀粉的分子模型，并通过计算机模拟进行了研究。首先，构建了不同长度的单螺旋和双螺旋。研究了支链淀粉双螺旋和单螺旋中的1 -> 6分支。单螺旋、双螺旋和分支点的亚基被用作更大系统的构建块。通过一系列模型（包括单-单、双-单和双-双螺旋系统）研究了支链淀粉单元簇的可能组成。连接两个分支点（内链）的单螺旋部分的长度在0-10个葡萄糖残基的值之间系统地变化。发现某些内部链长度导致平行双螺旋。因此，据推测，内部链的长度可以决定局部结晶度的程度。此外，注意到一些低能量排列的双螺旋可以叠加在结晶A和B淀粉多晶型物的两个相邻和不相邻的双螺旋上。在其他情况下，双螺旋之间的距离是如此之大，以至于它实际上可能是两个支链淀粉晶体或单元簇之间的分支模型。通过这项工作得到的结果证实，在可能的情况下，从晶体学，分支和酶的研究提供的信息。
Molecular models of amylopectin were created and investigated by computer simulation. First, single and double helices of various lengths were constructed. The 1 --> 6 branching in double and single helices of amylopectin was studied. Subunits of single helices, double helices, and branch points were used as building blocks of larger systems. The possible makeup of amylopectin unit clusters was investigated via a series of models, including single-single, double-single, and double-double helix systems. The lengths of the single helix section that linked two branch points (internal chains) was systematically varied between values of 0-10 glucose residues. It was found that certain internal chain lengths lead to parallel double helices. Thus, it was postulated that the length of internal chains may determine the degree of local crystallinity. Furthermore, it was noted that some of the low-energy arrangement of double helices could be superimposed on either the two adjacent and nonadjacent double helices of crystalline A and B starch polymorphs. In other cases, the distance between the double helices is so large that it may in fact be a model for branching between two amylopectin crystals or unit clusters. Results obtained through this work were corroborated, where possible, with information available from crystallographic, branching, and enzymatic studies.